, 2006 and Sutherland and Leathwick, 2011). The global spread of AR in sheep, goats and horses, coupled with the emerging problem of AR in cattle, mandates the development of new products and the implementation of more sustainable application strategies to ensure adequate parasite control in the future. Such strategies may include the use of anthelmintic combinations to forestall productivity losses due to AR, along with the discovery and development of novel anthelmintics.

New drugs may well exhibit a reduced spectrum compared to currently available drugs, but could provide effective parasite control in regimens compatible with current (localized) management practices if developed as combination products. This situation supports the contention that current anthelmintic combination guidelines are inadequate and a consensus is urgently needed to motivate and Dolutegravir mouse facilitate new product development and regulatory approval. Anthelmintic combination products incorporating two or more constituent actives are also used to expand the spectrum of efficacy against nematode parasites. For example, a new anthelmintic, derquantel (spiroindole class), has recently been approved for use in some countries as a combination anthelmintic product Selleck AG14699 with abamectin (ML class). By

adding abamectin to derquantel, the spectrum of parasite species against which this combination exhibits ≥95% efficacy is significantly increased (Little

et al., 2010 and Little et al., 2011). There is precedence for licensing anthelmintic combination products incorporating two or more constituent actives to expand efficacy against helminth parasites to include organisms in more than one phylum (i.e., nematodes plus trematodes or cestodes). These combination products are often developed based more on a combination of commercial interest and convenience for the end-user than on rigorous considerations of differences in the epidemiology of the disparate helminth targets of the constituent actives. Combinations of a broad-spectrum anthelmintic with a flukicide (e.g., clorsulon or triclabendazole) or cestocide (e.g., praziquantel) are and available world-wide, for instance, but the appropriate timing of fluke treatment may be an inappropriate time for nematode treatment. While it is legitimate to be concerned that anthelmintic combination products may promote indiscriminate or over-use of the product, the commercial reality is that veterinary pharmaceutical companies develop these products in response to producer demands and seek regulatory approval on this basis. Moreover, they mitigate the risk that end-users will dose animals with self-prepared ‘cocktail’ mixtures that could contain incompatible components, including excipients, or that may be dosed at incorrect rates.